U.S. patent number 10,675,476 [Application Number 15/847,435] was granted by the patent office on 2020-06-09 for internal thoracic vein placement of a transmitter electrode for leadless stimulation of the heart.
This patent grant is currently assigned to CARDIAC PACEMAKERS, INC.. The grantee listed for this patent is CARDIAC PACEMAKERS, INC.. Invention is credited to John Morgan, G. Shantanu Reddy, Kenneth Martin Stein.
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United States Patent |
10,675,476 |
Reddy , et al. |
June 9, 2020 |
Internal thoracic vein placement of a transmitter electrode for
leadless stimulation of the heart
Abstract
Implantable medical device systems and methods of use including
an implantable first medical device having a lead with a transducer
thereon and an implantable second medical device having a receiver
for receiving energy emitted by the transducer. The lead may be
placed in an internal thoracic vein, and other locations may be
used as well. The implantable second medical device may be placed
in or on the heart or an associated blood vessel.
Inventors: |
Reddy; G. Shantanu
(Minneapolis, MN), Stein; Kenneth Martin (Minneapolis,
MN), Morgan; John (Houghyon, GB) |
Applicant: |
Name |
City |
State |
Country |
Type |
CARDIAC PACEMAKERS, INC. |
St. Paul |
MN |
US |
|
|
Assignee: |
CARDIAC PACEMAKERS, INC. (St.
Paul, MN)
|
Family
ID: |
62625905 |
Appl.
No.: |
15/847,435 |
Filed: |
December 19, 2017 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20180178018 A1 |
Jun 28, 2018 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62438299 |
Dec 22, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N
1/3787 (20130101); A61N 1/37288 (20130101); A61N
1/37512 (20170801); A61N 1/0563 (20130101); A61N
1/37211 (20130101); A61N 1/3756 (20130101) |
Current International
Class: |
A61N
1/378 (20060101); A61N 1/372 (20060101); A61N
1/375 (20060101); A61N 1/05 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2016148928 |
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Sep 2016 |
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WO |
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2016149262 |
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Sep 2016 |
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WO |
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Other References
Moeinipour et al., "A Rare Central Venous Catheter Malposition: A
Case Report," Anesth Pain Med., 4(1): 1-3, Feb. 5, 2014. cited by
applicant .
Schuder et al., "Experimental Ventricular Defibrillation with an
Automatic and Completely Implanted System," Trans. Amer. Soc.
Artif. Int. Organs, XVI: 207-212, 1970. cited by applicant .
Schuder et al., "The Role of an Engineering Oriented Medical
Research Group in Developing Improved Methods and Devices for
Achieving Ventricular Defibrillation: The University of Missouri
Experience," PACE, 16: 95-124, Jan. 1993. cited by applicant .
Ghosh et al., "A Rare Malposition of the Thoracic Venous Catheter
Introduced via the Left Internal Jugular Vein," Indian J. Grit.
Care Med., 12(4): 201-203, Oct.-Dec. 2008. cited by applicant .
Loukas et al., "The Clinical Anatomy of the Internal Thoracic
Veins," Folia Morphol, 66(1): 25-32, 2007. cited by applicant .
Advisory Action Before the Filing of an Appeal Brief for U.S. Appl.
No. 15/667,167, dated Mar. 21, 2019. cited by applicant .
Final Office Action for U.S. Appl. No. 15/667,167, dated Jan. 10,
2019. cited by applicant .
Non-Final Office Action for U.S. Appl. No. 15/667,167, dated Jun.
26, 2018. cited by applicant .
Non-Final Office Action for U.S. Appl. No. 15/667,167, dated Aug.
7, 2019. cited by applicant .
Final Office Action for U.S. Appl. No. 15/667,221, dated Apr. 11,
2019. cited by applicant .
Non-Final Office Action for U.S. Appl. No. 15/667,221, dated Oct.
1, 2018. cited by applicant .
Notice of Allowance and Fees Due for U.S. Appl. No. 15/667,221,
dated Jul. 11, 2019. cited by applicant .
Amendment for U.S. Appl. No. 15/667,167, dated Sep. 17, 2018. cited
by applicant .
Amendment for U.S. Appl. No. 15/667,167, dated Oct. 9, 2019. cited
by applicant .
Amendment After Final Office Action for U.S. Appl. No. 15/667,167,
dated Mar. 11, 2019. cited by applicant .
Request for Continued Examination (RCE) for U.S. Appl. No.
15/667,167, dated Apr. 10, 2019. cited by applicant .
Amendment for U.S. Appl. No. 15/667,221, dated Dec. 21, 2018. cited
by applicant .
Amendment After Final Office Action for U.S. Appl. No. 15/667,221,
dated May 22, 2019. cited by applicant.
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Primary Examiner: Malamud; Deborah L
Attorney, Agent or Firm: Seager, Tufte & Wickhem LLP
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
The present application claims the benefit of and priority to U.S.
Provisional Patent Application Ser. No. 62/438,299, filed Dec. 22,
2016, and titled INTERNAL THORACIC VEIN PLACEMENT OF A TRANSMITTER
ELECTRODE FOR LEADLESS STIMULATION OF THE HEART, the disclosure of
which is incorporated herein by reference.
Claims
The claimed invention is:
1. An implantable medical device system comprising: a first lead
comprising a transducer for converting electrical energy to
mechanical energy; an implantable first medical device comprising a
canister housing operational circuitry for the implantable first
medical device, the implantable first medical device configured to
couple to the first lead, the operational circuitry including
driver circuitry for selectively driving the transducer of the
lead; and an implantable second medical device configured for
placement in the heart of a patient having a receiver for receiving
mechanical energy from the transducer and converting received
mechanical energy into electrical energy, and a plurality of
electrodes for delivering electrical pacing therapy to the heart of
a patient; wherein the first lead is configured for placement in an
internal thoracic vein of a patient such that the transducer
resides within the internal thoracic vein.
2. The system of claim 1 wherein the first lead comprises a
defibrillation electrode, and the implantable first medical device
comprises therapy circuitry for delivering a defibrillation therapy
using at least the defibrillation electrode of the first lead.
3. The system of claim 1 wherein the first lead comprises at least
one pacing electrode for outputting pacing therapy.
4. The system of claim 1 wherein the first lead comprises a
plurality of transducers that are separately addressable by the
driver circuitry for separately powering a plurality of implantable
second medical devices.
5. The system of claim 4 wherein the first implantable medical
device is configured to separately power the plurality of
implantable second medical devices by providing output power via
the plurality of transducers at a plurality of different transducer
frequencies.
6. The system of claim 1 wherein the operational circuitry of the
implantable first medical device comprises sensing circuitry for
receiving signals from electrodes disposed on the first lead, on a
second lead, or on the canister of the first medical device to
detect cardiac function.
7. The system of claim 6 wherein the operational circuitry is
configured to use the sensing circuitry to determine whether a
pacing therapy delivered by the second implantable medical device
has achieved a desirable outcome, and to adjust the driver
circuitry to increase or decrease an amount of power provided by
the driver circuitry to the transducer on the lead.
8. The system of claim 6 wherein the operational circuitry is
configured to use the sensing circuitry to determine whether a
pacing therapy delivered by the second implantable medical device
has achieved a desirable outcome, and to adjust the driver
circuitry to modify timing of power provided by the driver
circuitry to the transducer on the first lead.
9. A system as in claim 1 wherein the implantable first medical
device is configured to power and control therapy delivery by the
implantable second medical device by: providing power to the second
medical device using the transducer on the first lead; and
controlling operation of the second medical device by providing a
control signal within a power output generated using the
transducer.
10. A system as in claim 1 further comprising a second lead,
wherein the implantable first medical device comprises a header
adapted to receive each of the first and second leads, and further
wherein the second lead comprises a transducer for converting
electrical energy to mechanical energy, and the driver circuitry is
configured to selectively drive the transducer of the first lead
and the second lead separately.
11. The system of claim 1 wherein the canister is adapted for
placement in the left axilla of the patient, having a generally
rectangular shape.
12. The system of claim 1 wherein the canister is adapted for
placement near the left clavicle of the patient, having a generally
rectangular shape.
13. A method of treating a patient comprising: generating
mechanical energy using a first transducer located on a lead,
wherein at least a portion of the lead is located in an internal
thoracic vein of the patient; receiving the mechanical energy at a
second transducer on an implantable pacemaker located in or on the
heart of the patient; converting the mechanical energy to
electrical energy in the implantable pacemaker; and generating a
therapy output using the electrical energy with the implantable
pacemaker.
14. The method of claim 13 wherein the lead is coupled to an
implantable defibrillator comprising a housing containing one or
more batteries, sensing circuitry, therapy delivery circuitry, and
a driver for the transducer, the lead further including a
defibrillation coil electrode coupled to therapy delivery circuitry
located in the housing such that the subcutaneous defibrillator is
configured to: deliver defibrillation therapy using the housing and
the defibrillation coil in a shocking configuration; and provide
power to the leadless pacemaker using the driver and the transducer
on the lead.
15. The system of claim 14 wherein the housing is located
subcutaneously.
16. The method of claim 13 wherein the lead is coupled to an
implantable cardiac device comprising a housing containing one or
more batteries, sensing circuitry, and a driver for the transducer,
such that the implantable cardiac device is configured to: provide
power to the leadless pacemaker using the driver and the transducer
on the lead; and use the sensing circuitry to determine one or more
of an effectiveness of the leadless pacemaker output, a patient
cardiac state, or a patient activity level.
17. The system of claim 16 wherein the housing is located
subcutaneously.
18. The method of claim 13 wherein the first transducer is located
in the mediastinal space.
19. The method of claim 13 wherein the first transducer is located
in an intercostal vein connected to the internal thoracic vein.
20. The method of claim 13 wherein the first transducer is located
in the internal thoracic vein.
Description
BACKGROUND
The leadless cardiac pacemaker has the potential to change clinical
practice for those patients needing pacing therapy for bradycardia,
heart failure (cardiac resynchronization) and/or anti-tachycardia
treatments. Generally speaking the idea is to place a leadless
device entirely within the heart, a blood vessel of the heart, or
on the heart, without having lead attached thereto. Omission of the
lead would remove a source of reliability failures (due to lead
fracture) and avoid the potential for leads to block blood vessels,
interfere with valve function, and act as conduits for infection.
Some proposals for leadless cardiac pacemaker systems have
suggested receiving power from another implantable device. New and
alternative proposals that minimize power loss in the power
transfer for such systems are desired.
OVERVIEW
The present inventors have recognized, among other things, that a
problem to be solved is the need for more efficient transmission of
ultrasound energy to intracardiac ultrasound-powered pacemakers. In
some examples, a transducer, such as an ultrasound transmitter, is
placed on a lead that resides at least in part in an internal
thoracic vein (the right and/or left ITV) which is coupled to an
implantable canister. The transducer may stand alone on the lead,
or the lead may include one or more sensing or therapy delivery
electrodes. In another example, the transducer may be part of a
transmitter and defibrillation electrode. The transducer may be
used to power one or more stimulators placed in the chambers of the
heart, on the outside of the heart, or within one or more of the
coronary veins or other blood vessels. In an alternative, the lead
having the transducer may extend through one of the brachiocephalic
vein or an intercostal vein. In one such example the transducer,
alone or as part of a combination transmitter and electrode, may be
placed in an intercostal vein. In a still further alternative, the
lead may be placed by entering the internal thoracic vein and then
exiting the internal thoracic vein to enter the mediastinum,
allowing the transducer to be still closer to the heart. One
potential benefit of placing the transducer in this manner is that
the ribs will not block or attenuate the output mechanical energy,
unlike prior systems having a transducer placed over the
ribcage.
A first illustrative, non-limiting example takes the form of an
implantable medical device system comprising: a first lead
comprising a transducer for converting electrical energy to
mechanical energy; an implantable first medical device comprising a
canister housing operational circuitry for the implantable first
medical device, the implantable first medical device configured to
couple to the first lead, the operational circuitry including
driver circuitry for selectively driving the transducer of the
lead; and an implantable second medical device configured for
placement in the heart of a patient having a receiver for receiving
mechanical energy from the transducer and converting received
mechanical energy into electrical energy, and a plurality of
electrodes for delivering electrical pacing therapy to the heart of
a patient; wherein the first lead is configured for placement in an
internal thoracic vein of a patient.
Additionally or alternatively, the first lead may comprise a
combination transmitter and defibrillation electrode, of which said
transducer is a part, wherein the defibrillation electrode is a
coil electrode, and the implantable first medical device may
comprise therapy circuitry for delivering a defibrillation therapy
using at least the defibrillation electrode of the first lead.
Additionally or alternatively, the first lead may comprise a
defibrillation electrode, and the implantable first medical device
may comprise therapy circuitry for delivering a defibrillation
therapy using at least the defibrillation electrode of the first
lead.
Additionally or alternatively, the first lead may comprise at least
one pacing electrode for outputting pacing therapy.
Additionally or alternatively, the first lead may comprise a
combination transmitter and pacing electrode, of which said
transducer is a part.
Additionally or alternatively, the first lead may comprise a
plurality of transducers that are separately addressable by the
driver circuitry for separately powering a plurality of implantable
second medical devices.
Additionally or alternatively, the first implantable medical device
may be configured to separately power the plurality of implantable
second medical devices by providing output power via the plurality
of transducers at a plurality of different transducer
frequencies.
Additionally or alternatively, the operational circuitry may
comprise sensing circuitry for receiving signals from electrodes
disposed on the first lead, on a second lead, or on the canister of
the first medical device to detect cardiac function.
Additionally or alternatively, the operational circuitry may be
configured to use the sensing circuitry to determine whether a
pacing therapy delivered by the second implantable medical device
has achieved a desirable outcome, and to adjust the driver
circuitry to increase or decrease an amount of power provided by
the driver circuitry to the transducer on the lead.
Additionally or alternatively, the operational circuitry may be
configured to use the sensing circuitry to determine whether a
pacing therapy delivered by the second implantable medical device
has achieved a desirable outcome, and to adjust the driver
circuitry to modify timing of power provided by the driver
circuitry to the transducer on the first lead.
Additionally or alternatively, the transducer of the first lead may
be an ultrasound transducer.
Additionally or alternatively, the implantable first medical device
may be configured to power and control therapy delivery by the
implantable second medical device by: providing power to the second
medical device using the transducer on the first lead; and
controlling operation of the second medical device by providing a
control signal within a power output generated using the
transducer.
Additionally or alternatively, the implantable first medical device
comprises communication circuitry for communicating to the
implantable second medical device separate from the transducer of
the first lead, and the implantable first medical device is
configured to power and control therapy delivery by the implantable
second medical device by: providing power to the second medical
device using the transducer on the first lead; and controlling
operation of the second medical device by providing a control
signal using a communication output generated by the communication
circuitry.
Additionally or alternatively, the system may further comprise a
second lead, wherein the implantable first medical device comprises
a header adapted to receive each of the first and second leads, and
further wherein the second lead comprises a transducer for
converting electrical energy to mechanical energy, and the driver
circuitry is configured to selectively drive the transducer of the
first lead and the second lead separately.
A second illustrative, non-limiting example takes the form of a
method of treating a patient comprising: generating mechanical
energy using a first transducer located on a lead, wherein at least
a portion of the lead is located in an internal thoracic vein of
the patient; receiving the mechanical energy at a second transducer
on an implantable pacemaker located in or on the heart of the
patient; converting the mechanical energy to electrical energy in
the implantable pacemaker; and generating a therapy output using
the electrical energy with the implantable pacemaker.
Additionally or alternatively, the lead may be coupled to an
implantable defibrillator comprising a housing containing one or
more batteries, sensing circuitry, therapy delivery circuitry, and
a driver for the transducer, the lead may further include a
defibrillation coil electrode coupled to therapy delivery circuitry
located in the housing such that the implantable defibrillator is
configured to: deliver defibrillation therapy using the housing and
the defibrillation coil in a shocking configuration; and provide
power to the leadless pacemaker using the driver and the transducer
on the lead.
Additionally or alternatively, the lead may be coupled to an
implantable cardiac device comprising a housing containing one or
more batteries, sensing circuitry, and a driver for the transducer,
such that the implantable cardiac device is configured to: provide
power to the leadless pacemaker using the driver and the transducer
on the lead; and use the sensing circuitry to determine one or more
of an effectiveness of the leadless pacemaker output, a patient
cardiac state, or a patient activity level.
Additionally or alternatively, the first transducer may be located
in the mediastinal space.
Additionally or alternatively, the first transducer may be located
in an intercostal vein connected to the internal thoracic vein.
Additionally or alternatively, the first transducer may be located
in the internal thoracic vein.
Additionally or alternatively, the first transducer may be operated
at a duty cycle, relative to a 24 hour period, of at least 10%.
Additionally or alternatively, the first transducer may be operated
at a duty cycle, relative to a one hour period, of at least
10%.
A third illustrative, non-limiting example takes the form of a
method of implanting a medical device system, the medical device
system comprising a lead having a mechanical transducer thereon for
use in charging a leadless pacemaker and a canister housing a power
source and a driver for the transducer, the method comprising:
accessing the internal thoracic vessel (ITV) of a patient;
inserting at least a portion of the lead in the ITV; coupling the
lead to the canister; and implanting the canister.
Additionally or alternatively, the step of inserting at least a
portion of the lead in the ITV may include placing the lead such
that the transducer resides in the ITV.
Additionally or alternatively, the method may further comprise
accessing the mediastinum from the ITV; wherein the step of
inserting at least a portion of the lead in the ITV includes
placing the lead such that the transducer resides in the
mediastinum.
Additionally or alternatively, the method may further comprise
advancing at least a portion of the lead in or through an
intercostal vein.
Additionally or alternatively, the method may further comprise
advancing at least a portion of the lead in or through a
brachiocephalic vein.
This overview is intended to provide an introduction to the subject
matter of the present patent application. It is not intended to
provide an exclusive or exhaustive explanation of the invention.
The detailed description is included to provide further information
about the present patent application.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, which are not necessarily drawn to scale, like
numerals may describe similar components in different views. Like
numerals having different letter suffixes may represent different
instances of similar components. The drawings illustrate generally,
by way of example, but not by way of limitation, various
embodiments discussed in the present document.
FIG. 1 illustrates a prior art system for providing intracardiac
pacing with a subcutaneously placed ultrasound power source;
FIG. 2 shows portions of the human torso anatomy including certain
venous structures;
FIGS. 3-4 show implantation of illustrative cardiac therapy
systems;
FIGS. 5-8 show distal ends for a number of illustrative leads;
FIGS. 9-10 show illustrative leads in cross section;
FIGS. 11-13 show illustrative implantable devices adapted to
receive power from another implantable device;
FIG. 14 shows an illustrative implantable device adapted to provide
power to another implantable device;
FIG. 15 shows a human heart with several potential implant
locations for illustrative medical devices highlighted;
FIG. 16 shows a set of transducer locations that may be used in
several embodiments; and
FIG. 17 shows an implantable medical device system in block
form.
DETAILED DESCRIPTION
FIG. 1 illustrates a prior art system for providing intracardiac
pacing with a subcutaneously placed ultrasound power source. The
system shown generally resembles that of EBR Systems shown, for
example, in U.S. Pat. Nos. 7,953,493 and 8,315,701, and Auricchio
et al., FIRST-IN-MAN IMPLANTATION OF LEADLESS ULTRASOUND BASED
CARDIAC STIMULATION PACING SYSTEM: NOVEL ENDOCARDIAL LEFT
VENTRICULAR RESYNCHRONIZATION THERAPY IN HEART FAILURE PATIENTS,
Europace (2013) 15, 1191-1197.
In FIG. 1, the patient 10 with heart 12 has an implantable
pacemaker 14 implanted in the left ventricle. The pacemaker 14
comprises a receiver for receiving and converting ultrasound energy
into electrical energy, which is then used to deliver pacing
therapy output. The ultrasound energy is delivered by a transducer
18 that is coupled to a power supply housing 16. The transducer 18
is placed subcutaneously over the ribs of the patient, on the
anterior chest more or less level with the apex of the heart. The
power supply housing 16 contains the batteries that supply the
energy for the transducer 18, and is generally placed in the left
axillar (armpit) of the patient 10.
One concern with the original system as shown is that the batteries
in the power supply housing may be short lived. One solution is to
make the batteries rechargeable. Another solution is to improve the
power transfer from the transducer 18 to the pacemaker 14. The
power transfer is limited in part by anatomy, as the ribs are not
good conductors of ultrasound energy, and the placement of the
transducer 18 over the ribs increases the distance between the
transducer 18 and the pacemaker 14. The present invention is
directed at alternative designs and placement for the transducer,
among other potential benefits that will become apparent in the
following detained description.
FIG. 2 shows portions of the human torso anatomy including certain
venous structures. In FIG. 2 a human torso 40 is shown with
portions of the ribs and sternum omitted in order to allow the
heart 42 to be observed relative to several blood vessels. The
superior vena cava is shown at 44 with the brachiocephalic vein 46
feeding therein. More superior and lateral one observes the
subclavian vein 48, which is commonly used for implantation of
transvenous leads with intracardiac electrodes used in transvenous
pacemakers and defibrillators. The azygos vein is shown at 54 and
attaching to the posterior of the superior vena cava 46, running
posterior to the heart (as indicated by the phantom lines); the
azygos vein 46 has occasionally been noted as a potential implant
location for a lead or electrode for various cardiac and/or
neurological purposes.
The internal thoracic vein (ITV) is a vessel that drains the chest
wall and breasts. There are both left and right internal thoracic
veins on either side of the sternum, beneath the ribs. The ITV
arises from the superior epigastric vein and musculophrenic vein,
accompanies the internal thoracic artery along its course and
terminates in the brachiocephalic vein. In FIG. 2, the right ITV is
shown at 50, and the left ITV is shown at 52. The ITV has sometimes
also been referred to as the internal mammary vein, though such
usage has become less common in the literature. The ITV may be used
as an implantation location for a pacemaker or defibrillator lead,
as disclosed in are discussed in U.S. patent application Ser. No.
15/667,167, titled IMPLANTATION OF AN ACTIVE MEDICAL DEVICE USING
THE INTERNAL THORACIC VASCULATURE, the disclosure of which is
incorporated herein by reference.
Implantation may be achieved by accessing the superior epigastric
vein inferior to the lower rib margin and advancing a lead
superiorly into the ITV 50/52. Implantation may be achieved as well
by accessing the musculophrenic vein that runs along the lower rib
margin, and advancing a lead superiorly into the ITV 50/52.
Implantation may also be achieved by parasternal access through an
intercostal space and into the ITV 50/52. Parasternal access and
access via the superior epigastric or musculophrenic veins may be
achieved by first finding and entering the relevant vessel with a
cut-down or Seldinger technique (or other vascular access method),
using, for example, an ultrasonic needle to find the correct blood
vessel within the patient tissue.
In some examples, implantation may be achieved using a superior
access with entry using, for example, the subclavian vein 48,
advancing to the brachiocephalic vein and then through the ostium
and into the ITV 50/52. Again, any suitable vascular access method
including a cut-down or Seldinger technique may be used.
The ITV also receives blood flowing from the intercostal veins. The
intercostal veins run adjacent and inferior to the ribs, such as
with intercostal vein 58 that is shown alongside the 7.sup.th rib
56. Additional right side intercostal veins are shown at 60 and 62,
and left side intercostal veins are also shown including at 64. The
intercostal veins may also be used for implantation of a pacemaker
or defibrillator lead, as discussed in U.S. Provisional Patent
Application Ser. No. 62/437,063, titled IMPLANTATION OF AN ACTIVE
MEDICAL DEVICE USING THE INTERCOSTAL VEIN, the disclosure of which
is incorporated herein by reference. The present inventors have
determined that, in addition to, or as an alternative to,
inserting, in one or both ITV, a therapy lead having
defibrillation, pacing, and/or sensing electrodes thereon, a lead
may include a transducer to provide energy to an intracardiac
pacing device such as a leadless cardiac pacemaker. In some still
further examples, the ITV may not be used and instead a lead may be
placed in the intercostal vein directly and to have the ultrasound
transducer reside therein or, alternatively, the lead may be
advanced posteriorly to the hemiazygos, accessory hemiazygos, or
azygos vein, with a transducer or one or more electrodes in any of
these veins.
FIGS. 3-4 show implantation of illustrative cardiac therapy
systems. Referring to FIG. 3, a system comprising a canister 100 is
shown implanted with a lead 102 having a transducer 104 placed in
the left ITV 106 of a patient. The implantation shown has the
canister 100 approximately at the anterior axillary line
(mid-axillary or posterior axillary lines may be used instead, or
other implant location). The lead 102 may be placed in one of
several ways. In one example, the lead 102 may be placed by using a
parasternal access to the ITV in an intercostal space; in another
example, the lead 102 may be placed by first entering the superior
epigastric vein or musculophrenic vein and then advancing
superiorly into the left ITV 106. In another example, access to an
intercostal vein is made at the pocket where the canister 100 is
located, and the lead 102 is advanced through the intercostal vein
and into the ITV; once in the ITV the lead 102 can then be advanced
superiorly.
In some examples, the transducer 104 may be the only element on
lead 102. In other example, the lead 102 may include one or more
pacing or sensing electrodes (and associated conductors) and/or one
or more defibrillation coil electrodes. In still other examples,
the transducer 104 may combine both a transducer element with an
electrode element such as one or more pacing/sensing electrodes
and/or a defibrillation coil electrode.
The transducer 104 can be powered by driver circuitry in the
canister 100 to transmit a signal to a leadless pacemaker 120 which
is shown, illustratively, in the left ventricle. The driver
circuitry may, for example, provide an output signal at a desired
ultrasound frequency, and the transducer converts the electrical
signal to a mechanical signal such as by a piezoelectric element
that vibrates in response to an applied signal. The leadless
pacemaker 120 may be placed as shown, anchored to the myocardium
inside the left ventricle using, for example, tines or a helical
screw, or other fixation.
The leadless pacemaker 120 may instead by placed on the outside of
the heart 108 on the left ventricle or in the coronary vasculature
such as in a coronary vein on a desired part of the heart. The
leadless pacemaker 120 may be placed in the right ventricle
attached to the septum or in the myocardium such as in an apical
position. The leadless pacemaker may instead be pleased in an
atrial position such as in the right atrium, attached to the
septum. Various possible implant locations are shown below in FIG.
15. The transducer 104 may be placed in the left ITV 106 or right
ITV 112, and the location for the transducer 104 may be selected to
bring it into proximity to the leadless pacemaker 120. Thus, in the
example shown, the transducer 104 is in the left ITV which may be
generally over the interventricular sulcus, the groove separating
the left and right ventricle; depending on patient anatomy the left
ITV may instead be more or less over the left ventricle. During
placement, visualization may be used, such as fluoroscopy, to allow
placement at a position more or less level with the leadless
pacemaker 120. In another example, the transducer 104 may be placed
in an intercostal vein such as on the left side of the patient to
place the transducer more laterally to a position over the left
ventricle itself. FIG. 16, below, shows various options for placing
the transducer in proximity to the leadless pacemaker.
FIG. 4 shows another example. Here, the canister 150 is again in a
left axillary position, and now a bifurcated lead (which may
instead be two separate leads in another example) is placed, with a
transducer 152 placed in the left ITV 160 and a therapy electrode
154 in the right ITV 162. For example, the therapy electrode 154
may include one or more coil electrodes for delivering higher
energy therapy such as cardioversion or defibrillation, and/or may
include one or more pacing or sense electrodes such as one or more
ring electrodes. Again, the transducer 152 is shown in proximity to
a leadless pacemaker 170.
An ultrasound transducer on a lead as shown in FIGS. 3-4 may use a
piezoelectric element coupled to a sources of electricity by one or
more conductors extending through the lead, such as disclosed in
U.S. Pat. No. 6,654,638, the disclosure of which is incorporated
herein by reference. In another example, the transmitter may take
the form of a thin film ultrasound transducer (see, e.g., U.S. Pat.
No. 9,440,258, for example). When energy is transmitted by the
transmission circuitry of the implantable pulse generator, the
transmission element generates a mechanical signal, preferably an
ultrasound signal, which is delivered across the tissue to the seed
pacemaker.
Delivery, tissue attachment and retrieval features may be included
in the leadless pacemaker including those features shown in US PG
Patent Publications 20150051610, titled LEADLESS CARDIAC PACEMAKER
AND RETRIEVAL DEVICE, and 20150025612, titled SYSTEM AND METHODS
FOR CHRONIC FIXATION OF MEDICAL DEVICES, the disclosures of which
are incorporated herein by reference. Delivery, fixation and
retrieval structures may also resemble that of the Micra.TM.
(Medtronic) or Nanostim.TM. (St. Jude Medical) leadless pacemakers,
or the WiSE CRT (EBR Systems, Sunnyvale, Calif.).
FIGS. 5-8 show distal ends for a number of illustrative leads. As
noted above, in several embodiments a lead may include a transducer
standing alone, a transducer and one or more of pacing, sensing
and/or defibrillation electrodes, and may include a combination
transducer/electrode design such as a combined defibrillation
electrode and transducer. The transducers may be designed to have
an ultrasound driver in the canister of the associated powering
device or may instead have a miniaturized ultrasound driver
integrated into the lead.
FIG. 5 shows an example lead 200, the distal end of which is shown
in an ITV 202. The design may include a proximal sensing electrode,
a transducer 206, and a distal sensing electrode 208. In this
example the lead 200 has a design which adopts a curvature to fix
it in place within the ITV 202 by pressing against opposing walls
thereof along its length. For implantation, the lead 200 may be
held in a straight configuration by inserting a straightening wire,
such as a stylet or guidewire, therein. Alternatively, the lead may
include one or more tines, expandable elements (such as a
stent-like design or inflatable member) or other fixation
apparatuses. Various fixation mechanisms and designs are shown in
U.S. patent application Ser. No. 15/667,167, titled IMPLANTATION OF
AN ACTIVE MEDICAL DEVICE USING THE INTERNAL THORACIC VASCULATURE,
the disclosure of which is incorporated herein by reference.
In some examples, rather than residing in the ITV 202, the lead may
exit the ITV and enter into the mediastinum. Such an approach is
described, for example, in U.S. patent application Ser. No.
15/814,990, titled TRANSVENOUS MEDIASTINUM ACCESS FOR THE PLACEMENT
OF CARDIAC PACING AND DEFIBRILLATION ELECTRODES, and Ser. No.
15/815,051, titled ELECTRODE FOR SENSING, PACING, AND
DEFIBRILLATION DEPLOYABLE IN THE MEDIASTINAL SPACE, the disclosures
of which are incorporated herein by reference.
In several examples herein, the lead may be placed without
entering, or contacting the heart. The transducer is placed, in
several examples, at a location which is beneath the ribs, or in
plane with the ribs, without entering or contacting the heart.
FIG. 6 shows another example. Here the lead 220 includes a distal
defibrillation coil electrode 222 and a proximal defibrillation
coil electrode 224, with a transducer 226 therebetween. A distal
tip pace/sense electrode is shown at 230 and a proximal pace/sense
electrode is shown at 232. Fixation designs and elements as
described above may also be included.
FIG. 7 shows another example. Here, the lead 240 includes a
combination defibrillation electrode and transducer 242, with a
plurality of sensing/pacing electrodes at 244, 246, 248. As shown
below in FIGS. 9-10, the combination electrode/transducer may
include a transducer within a coil, or the transducer may be
contained in a lumen within the lead.
FIG. 8 shows another example. Here, the lead 260 comprises first
and second transducers 262, 264 and a plurality of sense/pace
electrodes 266, 268, 270. The transducers 262, 264 may be
separately addressable by the device, or may operate in unison. In
one example, each transducer 262, 264 may be operable relative to a
common ground wire within the lead, with each having a separate
"hot" wire going thereto.
FIGS. 9-10 show illustrative leads in cross section. In FIG. 9, a
lead 300 is shown in a section view with a sheet-type piezoelectric
transducer 302 on the outside of the lead, with a defibrillation
coil 312 placed thereover. The piezoelectric transducer 302 is
driven by a pair of conductors 304, 306 acting as anode and
cathode, delivering a driver signal to the transducer 302 from a
driving circuit in an associated canister (FIG. 3, item 100, for
example). Additional conductors 308, 310 may be provided to couple
to the coil electrode 312 in lumens defined in the lead insulator
312.
FIG. 10 shows another example. Here, the lead 320 is again shown in
cross section, with a defibrillation coil 322 on the outside of the
lead body 328, coupled to a conductor 324 by weld, adhesive, and/or
staking, for example. A lumen 330 is provided and contains an
ultrasound transducer 332 on a carrier having one or more
conductors 334 in a transducer body 336.
In other examples, the outer coil 312 (FIG. 9) or coil 322 (FIG.
10) may be omitted such that the transducer is the sole active
element at a given axial location on the lead. Any suitable
electrode, conductor, and lead body material may be used, as
desired.
FIGS. 11-13 show illustrative implantable devices adapted to
receive power from another implantable device. Referring first to
FIG. 11, a relatively full function LCP is shown at 350. The LCP
350 is shown as including several electrodes at 352, 354, 356, 358,
360, 362 which may be used for therapy delivery, signal sensing,
and/or to support conducted communication.
A transducer is shown at 370. The transducer may include a
piezoelectric member to convert mechanical energy, and more
particularly an ultrasound signal, to electrical energy. Various
references have shown the receipt of acoustic power such as an
ultrasound signal for use in generating a therapy output. For
example, U.S. Pat. Nos. 3,659,615; 3,735,756; 5,193,539; 6,140,740;
6,504,286; 6,654,638; 6,628,989; 6,764,446; 7,890,173; 9,180,285;
9,343,654; and 9,452,286, for example, as well as U.S. Patent
Application Publications 2002/0077673; 2004/0172083; and
2004/0204744, the disclosures of which are incorporated herein by
reference. The transducer 370 converts the received mechanical
signal into an electrical signal which can then be rectified and
smoothed and/or stored on a capacitor or rechargeable battery as
part of an energy storage module 372. The energy storage module 372
may further include a non-rechargeable or "primary" battery
cell.
Though not shown, a retrieval feature may be included, for example,
as an opening on or near the transducer to allow a retrieval tool
to attach thereto. A number of tines (not shown) may extend from
the device in several directions. The tines may be used to secure
the device in place within a heart chamber. An attachment structure
may instead take the form of a helical screw, if desired. In some
examples, tines are used as the only attachment features. As noted
above, delivery, tissue attachment and retrieval features may be
included in the LCP including those features shown in US PG Patent
Publications 20150051610, and/or 20150025612, titled SYSTEM AND
METHODS FOR CHRONIC FIXATION OF MEDICAL DEVICES, for example.
Delivery, fixation and retrieval structures may also resemble that
of the Micra.TM. (Medtronic) or Nanostim.TM. (St. Jude Medical)
leadless pacemakers, or the WiSE CRT (EBR Systems, Sunnyvale,
Calif.). Some fixation examples are also shown below.
The device 350 is shown with several functional blocks including a
processing module 372 which may include, for example, one or more
microprocessors and associated memory, input/output and/or logic
circuitry, or any other suitable circuitry, to allow instructions
to be stored and executed as needed. The processing module 380 may
additionally or instead include a state machine architecture.
The device is also shown with a communications module 382, a pulse
generator module 384, an electrical sensing module 386, and a
mechanical sensing module 388. In some examples, the electrical
sensing module 386 and mechanical sensing module 388 may be
configured to sense one or more biological signals for use in one
or more of determining timing for cardiac resynchronization therapy
(CRT), identifying physiological conditions, such as those
affecting the parasympathetic nervous system that may affect CRT
timing needs, and/or for assessing CRT efficacy, as further
described below. The mechanical sensing module 388 may
alternatively include a motion sensor to detect whether the patient
is active or not in order to support a rate adaptive pacing
protocol that increases the pacing rate when the patient is active.
In still other examples, the mechanical sensing module may include
a temperature sensor, a chemical sensor, a heart sound sensor, or
any other sensor, to provide information to support any of pacing,
rate adaptive pacing, CRT, or to provide diagnostics to aid in
patient condition determinations.
The processing module 380 may receive data from and generate
commands for the other modules 382, 384, 386, 388. Processing
module 380 may also obtain information from and/or control
operations in the transducer and/or energy storage module. For
example, if a rechargeable battery is being used, the processing
module (or the energy storage module 372) may determine when to
turn on or off the pulse generator module if the rechargeable
battery is running low. In another example, the processing module
may determine that the energy storage module 372 is running low and
then use the communications module 382 to request recharging from a
separate implantable device. In addition, the processing module 380
and/or energy storage module and/or transducer may include
over-charge and/or over-voltage protection circuitry, zero volt
recharge circuitry (to prevent damage to the energy storage module
on recovery from a complete discharge of the energy storage module
372) and any other suitable features to enhance reliability and/or
protect patient safety in relation to the use of a transducer and
energy storage module 372.
Various details and/or examples of internal circuitry, which may
include a microprocessor or a state-machine architecture, are
further discussed in US PG Patent Publications 20150360036, titled
SYSTEMS AND METHODS FOR RATE RESPONSIVE PACING WITH A LEADLESS
CARDIAC PACEMAKER, 20150224320, titled MULTI-CHAMBER LEADLESS
PACEMAKER SYSTEM WITH INTER-DEVICE COMMUNICATION, 20160089539,
titled REFRACTORY AND BLANKING INTERVALS IN THE CONTEXT OF
MULTI-SITE LEFT VENTRICULAR PACING, and 20160059025, titled,
MEDICAL DEVICE WITH TRIGGERED BLANKING PERIOD, as well as other
patent publications. Illustrative architectures may also resemble
those found in the WiSE CRT (EBR Systems, Sunnyvale, Calif.);
Micra.TM. (Medtronic) or Nanostim.TM. (St. Jude Medical) leadless
pacemakers. Circuity useful in relation to the recharging
circuitry, communication circuitry, and/or pulse generator
circuitry, may also be found in U.S. Pat. Nos. 7,177,698, and
7,437,193, the disclosures of which are incorporated herein by
reference.
FIGS. 12-13 show leadless pacemakers with reduced functionality. In
FIG. 12, a device 400 includes tines 402, 404 for fixation on one
end thereof. Electrodes are shown as ring electrodes at 410, 412
for therapy delivery. A removal feature 418 is shown as a grasping
hole for receiving a retrieval tool on a tab 416 extending out from
the body of the device.
A transducer is shown at 414 for receiving mechanical energy and
converting the mechanical energy into electrical energy. The
outputs of the transducer 414 may feed more or less directly to the
electrodes 410, 412 for therapy output, making this device purely a
receive--and--deliver system. Regulating and/or control circuitry
may be included to, for example, prevent therapy delivery below a
received energy threshold and/or cap the therapy output within a
safety margin.
A direct feed of the signal may be deliver a sinusoidal output
therapy signal. If desired, additional rectification and control
circuitry may be provided to further shape the therapy output, if
desired, to yield, for example, a square wave in a monophasic or
biphasic form. For example, the transducer signal 414 may go
through a rectifier to a smoothing capacitor to generate more or
less constant, monophasic signal. A switch relying on timing
circuitry (such as a timing capacitor) may be provided to reverse
polarity at some predefined interval. In order to allow a single
device to be addressed, the transducer and associated circuitry may
be tuned to a particular frequency, allowing only ultrasound
frequency within a predefined bandwidth to generate a response,
avoiding the potential for interference form known sources such as
therapeutic or imaging ultrasound, if desired, or allowing a single
leadless device among several implanted devices to be addressed by
selecting an appropriate frequency band.
FIG. 13 illustrates a hybrid device. The device 450 again includes
tines 452 for fixation and a removal feature shown at 454 on tab
456. Other fixation designs may be used instead. A number of
electrodes are provided, this time as posts rather than rings, and
shown at 460, 462, 464, 466. A transducer 470 for receiving
mechanical energy and converting to electrical energy delivers
current/voltage to an energy storage block at 472. A control
circuit is shown at 474, and a sensing circuit is shown at 476.
This system may use the control circuitry to control therapy output
using the electrodes 460, 462, 464, 466, with power from the energy
storage block 472.
The concept may be to provide a short term "rechargeable" device,
with an expected rechargeable life of, for example, seven days or
less, for example, a device capable of going one to three days
between charging may be used. In such a case, recharging may occur
while the patient is at rest (at night, for example), when the
delivered power will not encounter outside interference and/or the
patient is not moving, preferably making energy delivery more
efficient. The patient's rest may be identified by using a motion
sensor in the charging device (patient still and laying down), by
reference to a system clock (night time), or by observation of
cardiac rate trends over a period of time (slowing and steady).
Other charge periods may be used instead.
The sensing circuit 476 may offer capabilities such as including an
activity sensor or any of the functions noted above with respect to
the mechanical sensing block in FIG. 11, and/or may offer sensing
capabilities relative to electrical signals such as the ECG. In one
example, the sensing circuit is used for sensing electrical signals
received at the electrodes 460, 462, 464, 466 in order to observe
for conducted communication. For example, a separate device may
issue ultrasound energy to trigger (or power) the device 450 to
enter a listening phase with the sensing circuit, and then a 1-way
or 2-way communication session may take place by conducted
communication.
Data exchanged by conducted communication may include, for example,
request or commands for therapy delivery, adjustments to delivered
therapy, information related to patient condition (such as patient
activity level), or any other suitable input. For example, a second
device may use conducted communication to coordinate a pace capture
testing sequence, or a second device may use conducted
communication to command or adjust resynchronization therapy
delivery. Some illustrative interactions are discussed in U.S.
patent application Ser. No. 15/633,517, titled CARDIAC THERAPY
SYSTEM USING SUBCUTANEOUSLY SENSED P-WAVES FOR RESYNCHRONIZATION
PACING MANAGEMENT, Ser. No. 15/684,264, titled CARDIAC
RESYNCHRONIZATION USING FUSION PROMOTION FOR TIMING MANAGEMENT,
Ser. No. 15/684,366, titled INTEGRATED MULTI-DEVICE CARDIAC
RESYNCHRONIZATION THERAPY USING P-WAVE TO PACE TIMING, Ser. No.
15/710,118, titled MULTI-DEVICE CARDIAC RESYNCHRONIZATION THERAPY
WITH MODE SWITCHING TIMING REFERENCE, and Ser. No. 15/793,475,
titled MULTI-DEVICE CARDIAC RESYNCHRONIZATION THERAPY WITH TIMING
ENHANCEMENTS, the disclosures of which are incorporated herein by
reference.
Return communication may be issued by the device 450, for example,
to indicate completion of a charging session, to annunciate device
history or error issues, or for any other suitable purpose. The
implantable device 450 may be configured to deliver an output
signal, therapeutic or otherwise (such as one or more signal
outputs of very short duration, shorter than chronaxie, for
example) for receipt by the charging device upon completion of
charging.
The control circuit 474, which may be a state machine, an
application specific integrated chip, or even a controller, but is
more likely a set of logic configured for certain relatively
limited function and power consumption, then controls delivery of
pacing therapy using, for example, the sensing circuit 476 to
determine whether rate adaptive pacing is needed and/or to assist
in evaluating pace capture, efficacy, or any other suitable
diagnostic. At intervals, such as at daily intervals or when the
patient is determined to be resting, the charging of the implanted
device using the transducer 470 may be initiated.
FIG. 14 shows an illustrative implantable device adapted to provide
power to another implantable device. The illustration indicates
various functional blocks within a device 500, including a
processing block 510, memory 512, power supply 514, input/output
circuitry 518, therapy circuitry 520, and communication circuitry
522. These functional blocks make up at least some of the
operational circuitry of the device. The I/O circuitry 518 can be
coupled to one or more electrodes 504, 506 on the housing 502 of
the device 500, and may also couple via a header 526 for attachment
to one or more leads 530 having additional electrodes 532, 536, 538
and at least one transducer 534.
The processing block 510 will generally control operations in the
device 500 and may include a microprocessor or microcontroller
and/or other circuitry and logic suitable to its purpose. A state
machine may be included. Processing block 510 may include dedicated
circuits or logic for device functions such as converting analog
signals to digital data, processing digital signals, detecting
events in a biological signal, etc. The memory block 512 may
include RAM, ROM, flash and/or other memory circuits for storing
device parameters, programming code, and data related to the use,
status, and history of the device 500 and/or a paired second device
such as a leadless pacemaker as shown above in FIGS. 11-13 and
elsewhere.
The processing block 510 may be coupled to an activity sensor to
detect patient movement, posture, activity, etc. Such an activity
sensor may be provided in the device 500, or may be on an
associated device such as a leadless pacemaker as shown above, with
patient movement, posture or activity data communicated to the
processing block using conducted or other communication. The
processing block 510 may be configured to sense cardiac activity,
such as to identify a cardiac state of the patient (normal sinus,
sinus tachycardia, ventricular or atrial arrhythmia, etc.), and/or
to determine a need for therapy such as by identifying asystole or
a long pause or a ventricular arrhythmia such as ventricular
fibrillation. The processing block 510 may be configured to observe
cardiac activity using electrical inputs (captured using electrodes
532, 536, 528 and/or 504 and 506) or using other devices such as a
heart sound sensor, an accelerometer to detect cardiac motion, an
optical input to detect blood flow, etc. Such observed cardiac
activity may be used, as noted already, for arrhythmia
identification, but it may also be used to tailor and/or optimize
therapy such as by observing whether pacing therapy delivery from a
leadless pacemaker is capturing the heart or otherwise having an
intended effect such as improving cardiac output and/or
synchronization.
Some examples of the use of a device such as device 500 to assist
in therapy management of a leadless pacemaker are discussed, for
example, in U.S. patent application Ser. No. 15/633,517, titled
CARDIAC THERAPY SYSTEM USING SUBCUTANEOUSLY SENSED P-WAVES FOR
RESYNCHRONIZATION PACING MANAGEMENT, Ser. No. 15/684,264, titled
CARDIAC RESYNCHRONIZATION USING FUSION PROMOTION FOR TIMING
MANAGEMENT, Ser. No. 15/684,366, titled INTEGRATED MULTI-DEVICE
CARDIAC RESYNCHRONIZATION THERAPY USING P-WAVE TO PACE TIMING, Ser.
No. 15/710,118, titled MULTI-DEVICE CARDIAC RESYNCHRONIZATION
THERAPY WITH MODE SWITCHING TIMING REFERENCE, and Ser. No.
15/793,475, titled MULTI-DEVICE CARDIAC RESYNCHRONIZATION THERAPY
WITH TIMING ENHANCEMENTS, the disclosures of which are incorporated
herein by reference.
For example, modifications to leadless pacemaker operation may
include suggesting or commanding changes in therapy timing, therapy
type, and/or therapy amplitude or other parameters, for example the
processes described in the above referenced U.S. patent application
Ser. Nos. 15/633,517, 15/684,264, 15/684,366, 15/710,118, and
15/793,475. Data of this sort may be encoded in the ultrasound
energy output of a transducer by, for example, varying a frequency
or duration of output energy or duty cycle, or including spikes or
gaps in the output to cause perturbations that may be detected by
the leadless pacemaker. In other examples, data to modify leadless
pacemaker operation may be communicated using conducted or other
communications such as RF communication.
For example, the I/O circuitry 518 may filter and amplify cardiac
signals to be provided to the processing circuitry 510 which uses
instructions and parameters provided in memory to determine one or
more of the following: Whether therapy has been delivered by the
leadless pacemaker at a desired time relative to an R-wave, a
P-wave, or a prior therapy output Whether therapy delivered by the
leadless pacemaker has evoked a desired response from the heart,
such as triggering a ventricular contraction, or triggering a
fusion beat for cardiac resynchronization therapy The device 500
may include, in an example, rather than an electrode at 506, an
acoustic sensor or accelerometer to capture heart sounds or motion
(the sensor may instead be on the lead 530) indicating whether the
cardiac function is responding to pacing therapy from the leadless
pacemaker to cause ventricular contraction or cardiac
resynchronization. The device 500 may include, in an example, an
optical sensor rather than an electrode at 506 to observe blood
flow, or a sensor may be placed on the lead 530, to determine
pulsatile blood flow or blood flow velocity to observe cardiac
function in response to a pacing therapy delivery.
The power supply 514 typically includes one to several batteries,
which may or may not be rechargeable depending on the device 500.
For rechargeable systems there would additionally be charging
circuitry for the battery including for example a coil 516 for
receiving energy and regulating and rectification circuitry to
provide received energy to a rechargeable battery or
supercapacitor.
The I/O circuitry 518 may include various switches or multiplexors
for selecting inputs and outputs for use. I/O circuitry 518 may
also include filtering circuitry and amplifiers for pre-processing
input signals. In some applications the I/O circuitry will include
an H-Bridge to facilitate high power outputs, though other circuit
designs may also be used. Therapy block 520 may include capacitors
and charging circuits, modulators, and frequency generators for
providing electrical outputs. The therapy block and/or I/O block
518 includes driver circuitry for driving the transducer 534 with
an ultrasound-frequency range signal. For example, the driving
frequency may be in the range of about 20 kHz to about 10 MHz. The
driver and transducer 534 may be designed to have a controllable
frequency to allow separate addressing of multiple implanted
devices that are appropriately tuned.
In some examples, the I/O circuitry 518 and therapy block 520 may
be designed such that one or a pair of contacts in the header 526
are dedicated for use as mechanical transducer drivers. In other
examples, the driver circuitry for mechanical transducer may be
multiplexed with other I/O circuits. Thus, for example, any
contact, or several contacts, in the header 526 may be configurable
for use as sense-receive signal contacts, pace or defibrillation
electrical therapy outputs, and/or coupling to a mechanical
transducer 534 in the lead 530.
In one example, the driver circuitry provides a single output which
is routed to different output contacts in the header 526 to drive
separate transducers in the lead 530 or a plurality of leads, with
different transducers being addressed at different times using a
switch network of the I/O circuit. For this example, the driver
circuit may generate outputs at different frequencies at different
times to use a given transducer for a selected purpose. Thus, for
example, a system may have a first transducer located on a first
lead in the right ITV for delivering energy to a first leadless
pacemaker in the right ventricle (the "RV device"), and a second
transducer located on a second lead in the left ITV for delivering
energy to a second leadless pacemaker located in a coronary vein on
the left side of the heart (the "LV device"). To achieve
selectivity, the driver circuit may generate a first output tuned
for the RV device using a first frequency at a first time and using
a first combination of contacts in the header as selected using the
I/O circuitry thus coupling the signal to the first transducer, and
also generates a second output tuned for the LV device using a
second frequency at a second time that does not overlap the first
time and using a second combination of contacts in the header as
selected using the I/O circuitry thus coupling the signal to the
second transducer. In other examples, the driver circuit may have
multiple outputs and/or may be capable of generating multiple
outputs at a given time.
In still other examples, all the leadless pacemakers in a given
system may use the same, or at least similar, frequencies to
receive mechanical energy, and the frequency selectivity may be
unnecessary; to optimize the output power usage, multiple
transducers may be powered at the same time at one frequency; if
desired, one transducer may be phase shifted to avoid destructive
interference of the signals and/or to prevent delivering too much
power at a given location due to constructive interference. Such
phase shifting may occur by placing a variable filter element in
line with one of the output circuits. If interference is a concern,
another solution may be to power only one transducer at a time.
The communication circuitry 522 may be coupled to an antenna 524
for radio communication (such as Medradio, ISM, Bluetooth, or other
radiofrequency protocol/band), or alternatively to a coil for
inductive communication, and/or may couple via the I/O circuitry
518 to a combination of electrodes 504, 506, 532, 534, 538, for
conducted communication. Communication circuitry 522 may include a
frequency generator/oscillator and mixer for creating output
signals to transmit via the antenna 524. Some devices 500 may
include a separate or even off-the shelf ASIC for the
communications circuitry 522, for example. For devices using
inductive communication an inductive coil may be included. Devices
may use optical or acoustic communication, and suitable circuits,
transducers, generators and receivers may be included for these
modes of communication as well or instead of those discussed
above.
As those skilled in the art will understand, additional circuits
may be provided beyond those shown in FIG. 14. For example, some
devices may include a Reed switch, Hall Effect device, or other
magnetically reactive element to facilitate magnet wakeup, reset,
or therapy inhibition of the device by a user, or to enable an MM
detection and/or MM protection mode(s).
A device as in FIG. 14 may be embodied as a subcutaneous
implantable defibrillator with the additional capability for
providing energy using transducer 534 to a second implantable
device. For example, transducer 534 may be on a separate lead that
is implanted in the ITV, while the device also uses a
subcutaneously placed lead for sensing and defibrillation
purposes.
FIG. 15 shows a human heart with several potential implant
locations for illustrative medical devices highlighted. A leadless
cardiac pacemaker as shown herein could be implanted at numerous
locations in or on the heart 550. For example, devices may be
implanted as shown at 552, 554, on the outside of the heart by the
left ventricle. A device may be implanted inside the left ventricle
as shown at 556. Devices may also be placed in the right ventricle,
for example at the apex as shown at 560 and/or into the
interventricular septum at 562. A device may be placed in the right
atrium if desired, as shown at 570, anchoring to the atrial septum.
An atrial position may be easier if the size and/or mass of the
device are reduced by using one of the less complex designs shown
above in FIGS. 12 and 13, as opposed to a more full-function device
as shown by FIG. 11 (though the device of FIG. 11 may still be
used). Devices may be affixed in place using tined or helical
structures as desired; the actual structures shown are merely
illustrative.
In some examples, multiple devices may be placed. For example, a
system may be designed with devices that are provided in sets, with
or without dedicated purposes (i.e. a set may include an LV device
and an RV device as well as an RA device--each having a dedicated
purpose--or a set may include devices A, B, C, each of which is
generic as to location), where each device in a set is tuned to
receive energy using a transducer at a different frequency. In
another example, the control circuitry of a device may be able to
set the transducer to tune to one of several predetermined
frequencies either as part of a preoperative setup of the device,
or by communication in-vivo. Such tuning may allow, for example: A
single extracardiac device to selectively activate a plurality of
implantable devices from one or more transducers by selecting an
output frequency A single extracardiac device to charge separately
each of a plurality of implantable devices from one or more
transducers using frequency selection Another scenario is that an
extracardiac device issues both a mechanical signal (using, for
example, ultrasound) as well as an electrical signal to selectively
activate or command pacing with different pace modules. For
example, a device as in FIG. 13 may sense for a conducted
communication signal to determine when to deliver therapy, while it
receives power via a transducer. This design would be different
from the Prior Art of FIG. 1 insofar as in the existing
commercially available (in Europe at least) system from EBR
Systems, a large subcutaneous transducer is used by the powering,
subcutaneous device, in order to ensure that enough power is output
to trigger the leadless cardiac pacemaker immediately. Assuming,
for example, that the pace therapy has a pulse width of 5 to 15
milliseconds and is delivered at a rate of 75 beats per minute, the
duty cycle of the EBR Systems transducer/transmitter would be about
(75*0.015/60)<2% relative to a one-minute time reference. While
some examples may facilitate on-demand pacing where the transducer
operation correlates to the pacing output, other examples may adopt
a different approach.
More particularly, in some examples, a smaller
transmitter/transducer may be used if the output power is lowered
and the duty cycle is increased to, for example, at least 10% or
even up to 100% relative to an extended time period such as a
minute, hour, or day, or longer. A range of about 20% to about 40%
may be used in some examples. At a duty cycle of, for example, 20%,
referenced to a day, the charging could take place in a bit under
five hours while the patient sleeps, for example, to charge for a
generally continuous block of time. A duty cycle of, for example,
20% relative to an hour would allow charging to be scheduled
throughout the day including, for example, charging for about
twelve minutes, or more, once every hour. Still shorter time
periods may be used.
While some examples will include the leadless pacemaker providing
an indication that charging is complete via, for example, conducted
communication, other examples may omit such a step. The leadless
pacemaker may, for example, communicate with the charging device
infrequently, such as daily or weekly, to configure pacing and
charging parameters. The operational circuitry of the charging
device will then set charging parameters to ensure that charging is
performed to keep the leadless pacemaker sufficiently charged for
its therapy burden. For example, the operational circuitry may
determine how often the leadless pacemaker would exhaust a fully
charged rechargeable battery or capacitor, and would trigger
recharging at times selected to avoid exhausting the leadless
pacemaker power supply; recharging cycles may thus be triggered
according to expected need, rather than on a periodic (hourly or
daily, for example) basis. Charging efficiency may also be
determined by querying the leadless pacemaker as to the duration of
time needed to charge its power supply from a known state of at
least partial discharge to a fully charged state; charging
efficiency may depend on patient physiology and device placement,
for example. Such processes may be performed by the implanted
system on its own, or may be facilitated by an external programmer
if desired.
The leadless pacemaker would receive power and store electrical
energy on a capacitor or rechargeable battery, for example. In such
a design, the leadless pacemaker may itself control therapy
delivery timing, or it may receive a signal, such as an
interruption in the transmitted mechanical energy or a separately
conveyed signal such as a conducted communication signal or an RF
or inductive signal, to trigger pacing therapy. The triggered
pacing therapy may comprise a single pacing pulse output or a
sequence of pacing such as a set of anti-tachycardia pacing
pulses.
A temperature sensor may be provided in proximity to the transducer
on the lead to monitor for any changes in temperature that may
suggest local heating at the transducer; in the event of heating
the transducer may be duty cycled off to avoid tissue damage,
discomfort, or malfunction. Similarly a temperature sensor may be
provided in association with the driver in the implantable device
housing. Cycling may be performed by, for example, turning a
transducer on for a period of, for example, one to twenty seconds,
and then turning the transducer off for a period of, for example,
one to sixty seconds.
Still further options for implantation of a leadless pacemaker may
include those shown in U.S. Pat. No. 8,103,359, the disclosure of
which is incorporated herein by reference. For example, a leadless
pacemaker may be provided in one of the coronary veins, with
recharging using an ultrasound (or other transducer) located as
shown in any of the various examples shown herein. Such a leadless
pacemaker may be implanted through anchoring to the blood vessel
wall, by using a bias member to create an anchoring position in the
blood vessel, or by attaching a short lead to secure the device in
place using a deployable coil or stent structure, as shown further
in the '359 patent. The inclusion of such anchoring structures,
which are generally deployed within a single blood vessel or
chamber of the heart, is within the intended meaning of a "leadless
pacemaker" as used herein.
FIG. 16 shows a set of transducer locations that may be used in
several embodiments. This example shows a device canister at 600
implanted in a position that is commonly used for transvenous
pacemakers, with two leads 610, 620 extending therefrom. A first of
the leads 610 extends into the left ITV and is shown with several
transducers at 612, 614 and 616 in the ITV. Optionally, one or more
transducers 640 may be implanted in an intercostal vein 642. The
other lead 620 extends across to the right ITV via the
brachiocephalic vein, and includes several transducers at 622, 624,
626. It is unlikely that a single device 600 would be used with six
or even seven transducers as shown; the Figure is provided for
illustration and it should understood that one or more of the
transducers shown may be omitted in an actual system. The patient
is shown as having a left ventricular leadless pacemaker 630, a
right ventricular leadless pacemaker 632, and an right
atrial/septal leadless pacemaker 634. Such a configuration may be
useful for heart failure, for example.
In another example, one or more of the illustrated leadless
pacemakers may also be implanted in a coronary vein as shown by
U.S. Pat. No. 8,103,359, the disclosure of which is incorporated
herein by reference. For example, a coronary vein (such as in the
coronary sinus) placed leadless pacemaker may be combined with a
right ventricular leadless pacemaker, with the device placed in the
coronary sinus providing LV pacing and/or sensing; one or both of
the leadless pacemaker devices may also receive energy from a
transducer located, for example, in the ITV, in an intercostal
vein, or even an azygos, hemiazygos, or accessory hemiazygos
location.
Depending on the specific locations of the implanted leadless
device 630, 632, 634, different ones of the transducers may be
selected to provide power; such selection may be based on proximity
and physician preference. For example, transducers 622, 624 may be
activated--individually or together--to power a nearby device in
the right atrium 634. Transducer 626 may be used to power a right
atrial device 632; if needed or desired (for example, if device 632
is quite medial compared to each ITV), transducer 616 may also be
used to power the right atrial device 632, alone or in combination
with transducer 626. Transducers 614, 616, and 640 (individually or
in combination) may be used to power the left ventricular device
630. If a patient has multiple implanted devices 630, 632, 634, the
different devices and associated transducers may be configured to
use uniquely selected frequencies or bands of frequencies to allow
the devices to be separately addressed. In some examples, on the
other hand, power transmission may occur at a single frequency for
all devices, with other signals provided to the individual devices
for control purposes using, for example, conducted communication,
or RF or inductive links.
In another example, the system may integrate multiple functions to
allow cardiac rhythm management, for example, heart failure or rate
adaptive pacing for a patient with a complete block. In such an
example, the leads 610, 620 may also include sensing electrodes to
allow sensing of atrial and/or ventricular signals for use in
providing cardiac resynchronization therapy (CRT) and/or to provide
ventricular pacing using atrial timing for a patient with complete
heart block.
FIG. 17 shows an implantable medical device system in block form.
The figure is designed to illustrate a large number of options and
combinations that can be achieved with the present invention.
A system may include a first implantable medical device (IMD),
shown at 700, which operates using at least one lead 720, and
provides power for use by a second IMD 760. The first IMD 700 may
be placed in various suitable locations in the patient including,
for example and as shown above, an axillary position 702 (such as
in the left axilla and/or near the anterior, mid, or posterior
axillary lines) or a pectoral position 704 (such as is in common
use for transvenous pacemakers and defibrillators, high on the
right or left chest near the clavicle).
The first IMD 700 may include the ability to sense and/or deliver
pacing and/or defibrillation therapy, as indicated at 706. For
example, the first IMD 700 may have sensing capabilities, including
without limitation, the ability to sense arrhythmia, cardiac
fusion, cardiac pace capture, asystole, patient
activity/motion/posture, surrogates for patient metabolic demand
(temperature, blood sugar, motion) or any other desired signal
and/or condition. Further the first IMD 700 may include therapy
output circuitry to provide pacing or defibrillation therapy. The
first IMD 700 may also include the ability to deliver
non-electrical therapy such as drug therapy.
The first IMD 700 may include a second lead, as indicated at 708.
The first IMD 700 may be a rechargeable device 712, or it may use a
primary battery that is non-rechargeable 714. In some examples, the
first IMD 700 includes both primary and rechargeable power supplies
in which some functions, such as those using the first lead 720 to
deliver power to the second IMD 760, are allowed only when
sufficient rechargeable power is available, while other functions,
such as the ability to sense for arrhythmia and deliver
defibrillation therapy, may be available regardless the
rechargeable battery status.
The first IMD 700 may also include circuitry to facilitate
communication to the second IMD 760 outside of the mechanical
signal noted at 750. Such communication may be used to interrogate
the second IMD 760 to determine its status, to load program
instructions to the second IMD 760, to provide information (such as
therapy efficacy) to the second IMD 760, and/or to provide commands
to the second IMD 760, as discussed in various embodiments above.
For example, the first IMD 700 may command a therapy output by the
second IMD, or the first IMD 700 may determine that the second IMD
760 can modify a therapy parameter and may communicate such to the
second IMD 760.
The lead 720 may be implanted at a number of locations 722 as
indicated above. Example locations may include in the mediastinum
724, in a brachiocephalic vein 726, in the ITV 728, or in an
intercostal vein 730. For example, a lead may be implanted in an
intercostal vein 730 after accessing the ITV 728 from the
brachiocephalic vein (as shown in FIG. 16). In another example, a
lead may be implanted in the mediastinum by accessing an
intercostal vein 730, for example, in the left axilla or at a
location near the sternum, or anywhere therebetween, passing the
lead to the ITV 728 from the intercostal vein 730, and then exiting
the ITV 728 to enter the mediastinum 724. Mediastinal placement
from the ITV is shown, for example, in U.S. patent application Ser.
No. 15/814,990, titled TRANSVENOUS MEDIASTINUM ACCESS FOR THE
PLACEMENT OF CARDIAC PACING AND DEFIBRILLATION ELECTRODES, and Ser.
No. 15/815,051, titled ELECTRODE FOR SENSING, PACING, AND
DEFIBRILLATION DEPLOYABLE IN THE MEDIASTINAL SPACE, the disclosures
of which are incorporated herein by reference.
The first lead 720 may have a number of design features 740. For
example, the lead may include one or more sensing electrodes 742,
one or more pacing electrodes 744, one or more defibrillation
electrodes 746, and/or one or more transducers 748 that can be used
to generate mechanical energy 750, such as an ultrasound output
signal. The second lead 708, if provided, may have similar such
items.
The first lead 720 is used to generate and transmit a mechanical
signal 750, which may be an ultrasound signal, to the second IMB
760. The second IMB 760 includes a transducer to receive the
mechanical signal 750.
The second IMD may be implanted in any of the positions 762 noted
above. For example, the second IMD may be implanted in one of the
chambers of the heart, on the outside of the heart, or within one
of the coronary veins or other blood vessels in, on, or adjacent to
the heart. There may be multiple second IMDs 760, as indicated at
764.
The second IMD 760 may be a passive device that is responsive to a
incoming mechanical signal to deliver therapy, as indicated at 766.
In other examples, the second IMD 760 may include a rechargeable
768 power supply, allowing the second IMD to exercise a level of
control, which can vary, over its therapy outputs by, for example
sensing cardiac signals to configure therapy and/or determine
whether and when to deliver therapy. A rechargeable 768 device may
receive commands to deliver therapy, or it may determine when to
deliver therapy using its own independent control system and/or
rules/parameters.
The second IMD 760 may also take the form of a hybrid 770 device
having both a primary battery and a rechargeable battery. The
functions of a hybrid 770 device may vary in response to the status
of the primary and/or rechargeable batteries. For example, the
second IMD 760 may be a leadless pacemaker and, if it is a hybrid
770 device, the pacemaker may deliver a life preserving pacing
therapy (such as a 30-50 bpm demand pacing output) when operating
under only primary cell power, and a more sophisticated pacing
output such as a rate adaptive pace therapy or CRT when operating
under rechargeable battery power.
The variables and features noted in FIG. 17 are provided for
illustrative and non-limiting purposes.
Following is a set of non-limiting examples. Each of these
non-limiting examples can stand on its own, or can be combined in
various permutations or combinations with one or more of the other
examples. The examples comprise references to elements of the
drawings associated with the first instance of the use of certain
terms, and it should be understood that such references further
incorporate the description of the numbered elements provided
above.
A first non-limiting example takes the form of an implantable
medical device system comprising: a first lead (102, 200, 220, 240,
260, 300, 320, 530, 610, 620, 720) comprising a transducer (104,
152, 206, 226, 242, 262, 264, 302, 332, 536, 612, 614, 616, 622,
624, 626, 640, 748) for converting electrical energy to mechanical
energy; an implantable first medical device (100, 150, 500, 600,
700) comprising a canister (502) housing operational circuitry
(510, 512, 514, 516, 518, 520, 522) for the implantable first
medical device, the implantable first medical device configured to
couple to the first lead, the operational circuitry comprising
driving means (as described above, an ultrasound driver output may
be included in blocks 518, 520, or may be integrated into the first
lead 102, 220, 220, 240, 260, 300, 320, 530, 610, 620) for
selectively driving the transducer of the first lead; and an
implantable second medical device (120, 170, 350, 400, 450, 552,
554, 556, 560, 562, 570, 630, 632, 634, 760) configured for
placement in, or on the heart of a patient or in a coronary vein
thereof, the implantable second medical device having a receiver
means (as described above, a transducer/receiver as shown at 370,
414, 470, 760) for receiving mechanical energy from the transducer
(104, 152, 206, 226, 242, 262, 264, 302, 332) and converting
received mechanical energy into electrical energy, and a plurality
of electrodes (352, 354, 356, 358, 360, 362, 410, 412, 460, 462,
464, 466) for delivering electrical pacing therapy to the heart of
a patient; wherein the first lead is configured for placement in an
internal thoracic vein (106, 112, 160, 162, 202) of a patient.
Insofar as the first lead is configured for placement in an
internal thoracic vein, it is meant here that the first lead has an
outer diameter, inclusive of the transducer, to facilitate
placement of at least a portion thereof in the internal thoracic
vein to place the transducer in the same plane as, or beneath, the
ribs of the patient.
Additionally or alternatively in or to the first non-limiting
example, the first lead comprises a combination transmitter and
defibrillation electrode, of which said transducer is a part,
wherein the defibrillation electrode is a coil electrode, and the
implantable first medical device comprises therapy means for
delivering a defibrillation therapy using at least the
defibrillation electrode of the first lead.
Additionally or alternatively in or to the first non-limiting
example, the first lead comprises a defibrillation electrode, and
the implantable first medical device comprises therapy means for
delivering a defibrillation therapy using at least the
defibrillation electrode of the first lead.
Additionally or alternatively in or to the first non-limiting
example, the first lead comprises at least one pacing electrode for
outputting pacing therapy.
Additionally or alternatively in or to the first non-limiting
example, the first lead comprises a combination transmitter and
pacing electrode, of which said transducer is a part.
A second non-limiting example incorporates the first non-limiting
example, wherein the first lead comprises a plurality of
transducers that are separately addressable by the driver means for
separately powering a plurality of implantable second medical
devices.
Additionally or alternatively in or to the second non-limiting
example, the driver means of the first implantable medical device
is configured to separately power the plurality of implantable
second medical devices by providing output power via the plurality
of transducers at a plurality of different transducer
frequencies.
A third non-limiting example incorporates the first and/or second
non-limiting examples, wherein the operational circuitry of the
implantable first medical device comprises sensing means (such as
using sense electrodes 742 and sensing, pacing and defibrillation
circuitry 706 in FIG. 17, and/or the combination of I/O circuitry
518 with processing circuitry 510 for analyzing cardiac signals
using instructions and parameters selected and set in memory 512 in
FIG. 14) for receiving signals from electrodes disposed on the
first lead, on a second lead, or on the canister of the first
medical device to detect cardiac function.
Additionally or alternatively in or to the third non-limiting
example, the operational circuitry comprises therapy determining
means coupled to the sensing means for determining whether a pacing
therapy delivered by the second implantable medical device has
achieved a desirable outcome (such as the combination of I/O
circuitry 518 with processing circuitry 510 for analyzing cardiac
signals using instructions and parameters selected and set in
memory 512 in FIG. 14 to determine therapy results of the therapy
delivered by the first medical device using tools and methods as
described above, such as those of several related patent
applications and concepts described above using one or more of
captured cardiac electrical signals, acoustic, motion, or optical
sensors), the therapy determining means coupled to adjustment means
for adjusting the driver means to increase or decrease an amount of
power provided by the driver means to the transducer on the lead
(such adjustment means may take the form of a set of instructions
in the memory causing the processing circuit 510 to make
adjustments to the driver means power level).
Additionally or alternatively in or to the third non-limiting
example, the operational circuitry comprises therapy determining
means for determining whether a pacing therapy delivered by the
second implantable medical device has achieved a desirable outcome
(such as the combination of I/O circuitry 518 with processing
circuitry 510 for analyzing cardiac signals using instructions and
parameters selected and set in memory 512 in FIG. 14 to determine
therapy results of the therapy delivered by the first medical
device using tools and methods as described above, such as those of
several related patent applications and concepts described above
using one or more of captured cardiac electrical signals, acoustic,
motion, or optical sensors), and adjusting means for adjusting the
driver means to modify timing of power provided by the driver means
to the transducer on the first lead (such adjustment means may take
the form of a set of instructions in the memory causing the
processing circuit 510 to make adjustments to the driver means
timing characteristics).
Additionally or alternatively in or to any of the first to third
non-limiting examples, the transducer of the first lead is an
ultrasound transducer.
Additionally or alternatively in or to any of the first to third
non-limiting examples, the implantable first medical device
operational circuitry is configured to use the driver means to
provide power to the second medical device using the transducer on
the first lead, and the operational circuitry further comprises
control means to modulate an output of the driver circuit to
provide a control signal within a power output generated using the
transducer (such modulation may be integrated as part of the
communication means 522 used to generated and control communication
outputs of the device 500).
Additionally or alternatively in or to any of the first to third
non-limiting examples, the implantable first medical device
operational circuitry is configured to use the driver means to
provide power to the second medical device using the transducer on
the first lead, and the operational circuitry further comprises:
communication means for communicating to the implantable second
medical device separate from the transducer of the first lead (such
as communication block 522 using conducted communication by way of
electrodes 504, 506, 532, 534, and/or 538, or using the antenna
524); and control means to identify and communicate, using the
communication means, directions for therapy delivery by the
implantable second medical device (such control means may include
stored operational instructions in the memory 512 for execution by
the processing block 510 controlling the communication block
522).
Additionally or alternatively in or to any of the first to third
non-limiting examples, the system comprises a second lead, wherein
the implantable first medical device comprises a header (526)
adapted to receive each of the first and second leads, and further
wherein the second lead comprises a transducer for converting
electrical energy to mechanical energy, and the driver means is
configured to selectively drive the transducer of the first lead
and the second lead separately.
Additionally or alternatively in or to any of the first to third
non-limiting examples, the implantable second medical device may
comprise a rechargeable battery or capacitor (noted at 372, 472,
and 768)coupled to the receiver means thereof to receive and store
energy received from the transducer of the first lead.
The above detailed description includes references to the
accompanying drawings, which form a part of the detailed
description. The drawings show, by way of illustration, specific
embodiments in which the invention can be practiced. These
embodiments are also referred to herein as "examples." Such
examples can include elements in addition to those shown or
described. However, the present inventors also contemplate examples
in which only those elements shown or described are provided.
Moreover, the present inventors also contemplate examples using any
combination or permutation of those elements shown or described (or
one or more aspects thereof), either with respect to a particular
example (or one or more aspects thereof), or with respect to other
examples (or one or more aspects thereof) shown or described
herein.
In the event of inconsistent usages between this document and any
documents so incorporated by reference, the usage in this document
controls.
In this document, the terms "a" or "an" are used, as is common in
patent documents, to include one or more than one, independent of
any other instances or usages of "at least one" or "one or more."
Moreover, in the following claims, the terms "first," "second," and
"third," etc. are used merely as labels, and are not intended to
impose numerical requirements on their objects.
Method examples described herein can be machine or
computer-implemented at least in part. Some examples can include a
computer-readable medium or machine-readable medium encoded with
instructions operable to configure an electronic device to perform
methods as described in the above examples. An implementation of
such methods can include code, such as microcode, assembly language
code, a higher-level language code, or the like. Such code can
include computer readable instructions for performing various
methods. The code may form portions of computer program products.
Further, in an example, the code can be tangibly stored on one or
more volatile, non-transitory, or non-volatile tangible
computer-readable media, such as during execution or at other
times. Examples of these tangible computer-readable media can
include, but are not limited to, hard disks, removable magnetic or
optical disks, magnetic cassettes, memory cards or sticks, random
access memories (RAMs), read only memories (ROMs), and the
like.
The above description is intended to be illustrative, and not
restrictive. For example, the above-described examples (or one or
more aspects thereof) may be used in combination with each other.
Other embodiments can be used, such as by one of ordinary skill in
the art upon reviewing the above description.
The Abstract is provided to comply with 37 C.F.R. .sctn. 1.72(b),
to allow the reader to quickly ascertain the nature of the
technical disclosure. It is submitted with the understanding that
it will not be used to interpret or limit the scope or meaning of
the claims.
Also, in the above Detailed Description, various features may be
grouped together to streamline the disclosure. This should not be
interpreted as intending that an unclaimed disclosed feature is
essential to any claim. Rather, inventive subject matter may lie in
less than all features of a particular disclosed embodiment. Thus,
the following claims are hereby incorporated into the Detailed
Description as examples or embodiments, with each claim standing on
its own as a separate embodiment, and it is contemplated that such
embodiments can be combined with each other in various combinations
or permutations. The scope of the invention should be determined
with reference to the appended claims, along with the full scope of
equivalents to which such claims are entitled.
* * * * *